景观植被生态系统水平衡模拟与分析

Simulation and Analysis of Water Balance for Vegetation Ecosystems on Landscape Scale

景观或区域的水平衡状况是全球变化的重要指标。本研究建立了一个空间显式景观过程模型，模拟了长白山自然保护区的水循环过程，并对水分收入、支出和平衡的总体状况、季节动态和空间分布格局进行了分析。整个保护区单位面积上水分盈余0．225±0．255m·a^-1，总计盈余4．379×10^8m^3·a^-1，但空间变异相当大。阔叶红松林的水分有略微亏缺，其他类型植被生态系统每年均有不同程度的水分盈余。从总面积上看，云冷杉林每年的水分盈余最多（可达1．696×10^8m^3·a^-1），占整个保护区的40．56％。整个保护区6月水分亏缺最严重，7～8月水分盈余最多，3～4月盈余较多。阔叶红松林除3月外，其他各月的水分亏缺均最多或次多，其中7～8月的水分盈余最少。降水量对水分收入、水分支出和水平衡季节动态的影响均最大。总的来说，年水分盈余的空间分布随海拔升高呈明显增加的趋势。气象因子均对水平衡的空间分布有极显著影响，气温和总辐射较高的地带，水分盈余较少，甚至出现水分亏缺；而降水量、相对湿度和风速较高的地带，水分盈余也较多。水分收入与叶面积指数（LAD呈极显著负相关关系；而水分支出与LAI呈极显著正相关关系，主要受蒸腾量的影响。

Water balance on landscape or region scale is the important indication of global change. Using a developed process-based spatial explicit landscape model, we simulated water cycling processes in Changbai Mountain Nature Reserve, and analyzed total statuses, seasonal variations and spatial pattems of water input, output and balance. The simulated average water surplus per unit area was 0. 225±0. 255 m· a^-1 , i.e. , 4. 379× 10^8 m^3 · a^-1 over the entire reserve with great spatial heterogeneity. In the whole, mixed broad-leaved and Korean pine forests lacked the little number of water, whereas the other vegetation ecosystems bad more or less water surplus. Considered in total areas, spruce-fir forests have the most annual water surplus （about 1. 696 × 108 m^3 · a^-1 ） accounting for 40. 56% of those for all the ecosystems. In June, the entire reserve had the most serious lack in water; on the contrary, in July and August, it had the most plenty of water, secondly more in March and April. Except in March, mixed broad-leaved and Korean pine forests had the most serious lack in water or the least water surplus （July and August） . The seasonal dynamics of precipitation had the most significant effects on those of water input, output and balance. The spatial pattern of annual water balance （surplus） values obviously increased with the increasing elevation gradient. Climatic factors had extremely significant influences on the spatial pattern of water balance： at the locations with higher air temperature and total solar radiation water surpluses were less, even water lacked; while at the locations with higher precipitation, relative moisture and wind speed water surpluses were more. Water input was highly negatively correlated with LAI mainly due to precipitation, while water output was highly positively correlated with LAI mainly due to transpiration.